Regensburg 2007 – scientific programme

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SYPE: Symposium Polyelectrolytes

SYPE 2: Polyelectrolytes I

SYPE 2.9: Talk

Thursday, March 29, 2007, 16:45–17:00, H37

Collapse of highly charged polyelectrolytes by dipole-dipole interactions — •Andrey Cherstvy and Roland Winkler — IFF, Forschungszentrum Jülich, D-52425 Jülich, Germany

Although collapse of highly charged polyelectrolytes (pe) was considered in a number of theoretical [1,2] and simulation [3-5] studies, some questions about effect of added salt and scaling relations for compact state remain open. We consider the influence of electrostatic (el) and dipole-dipole (dd) interactions on properties of flexible highly charged pes [6]. The dd interactions of pe segments are due to condensed counterions. We sum screened el and dd interactions along pe assuming that Gaussian statistics is weakly perturbed [7]. Attractive averaged dd interactions used are akin to Keesom energy. For weakly charged pe (below Manning limit), pes are swelled due to el repulsion of monomers. As condensation of counterions sets in, attractive dd interactions start to counteract el repulsion and trigger chain compaction into globules. We study onset on collapse as a function of chain length and salt conc. Scaling relations for size of the globule depending on pe charge density are obtained, with and without excluded volume interactions. We treat also the persistence length of dipolar chain and scaling relations for dense aggregates.

[1] H. Schiessel et al., MM 31 7953 (1998). [2] A.G. Cherstvy et al., JPCB 106 13362 (2002). [3] R.G. Winkler et al., PRL 80 3731 (1998). [4] R.G. Winkler et al., PRE 66 021802 (2002). [5] R.G. Winkler New J. Phys. 6 11 (2004). [6] A.G. Cherstvy and R.G. Winkler, in preparation. [7] S. Lifson et al. JPolSci XI 409 (1953).